seeding direct on raft question

[Dino Pantelidis]

So I've setup an indoor system on the 2nd floor of one of my restaurants in the hopes of being able to supply the restaurant with herbs, some lettuce etc. and have afew questions Im hoping to get help with!

Because of the limited space and the fact that I am "testing" at this point (if this goes well I will make more room!) I am attempting to plant my seeds direct rather than a seedling station.

This is what Im using so far:

1" dow blue board (Its difficult to find the 2" in Canada)

media: I've got hydroton and rockwool cubs

netcups are 2" I believe

Lighting options: 250 MH, or 300W LED (have not turned them on at this point)

I (think) because the foam rafters are only 1" it seems like the rockwool is taking in too much water. Has anyone used 1" foam rafters with rockwool and had success? Should I not be seeding direct, and have a station for growing out the seeds until they are large enough to go into the raft beds?

My tank is also very new and perhaps not full of nutrients yet, but I germinated some seeds in one of those plastic trays and transplanted them to the rafters, they just dont seem to be growing much. I've also planted some seeds in about 10 netcups afew days ago and still have not seen any action yet.

Sorry for all the silly questions, I'd love to hear some feedback/assistance!

[TCLynx]

You might be able to double up the foam to get the rafts to float higher and keep from water logging the rock wool.

I'm not big on the raft culture myself but I've started seeds directly in my "home made net pots" or yogurt cups with holes by using rayon mop string wicks to wick up enough moisture to germinate the seeds directly in the net pots without need for rock wool.  Here is my blog post about my "net pots" with wicks.

Now you might want to have a look at theplanting by the moon calendar since sometimes if you plant during the wrong time, you can get very dismal germination or very slow growth till the right moon phase swings around.

Temperature can also play a big roll in germination so if your water is too cold you might have poor germination trying to start the seeds right in the system.

[Vlad Jovanovic]

So far I've had great luck seeding directly into 2" net pots with just hydroton as a rooting media. Though I've never immediately floated them in water...

Temperature plays an important role while germinating. Use your 250 Watt MH and a cake dome to create a nice warm, moist environment for the seeds and they should germinate generally in a day or two. (Don't worry about providing a dark place for lettuce germination, as the light is actually a beneficial trigger for them to sprout). 

The nice thing about the cake domes are their price, availability, and they have a 'lip' along the bottom tray which easilly allows you to water from the bottom (once or twice a day, as needed. Also I've noticed that pre-soaking the hydroton in water before seeding helps).

I've read that people have had problems with root rot while germinating directly that way...That the problem shows up suddenly after 2 or 3 weeks? Again, just something I've read in the Friendly's manual...

You don't need any nutrients to sprout seeds.

[Dino Pantelidis]

Thanks guys;

Vlad: Do you use 2" foam rafts?

[Vlad Jovanovic]

I've used both 1" as well as 2". The lettuces and spinach in the photos are in 1" rafts. I've not had problems as I always wait 10-12 days after they've sprouted to place them in constant water. Also, like TC suggested, your Rockwool is probably water logging which would be bad for the seeds...

Also, I usually don't bother with the cover tray for lettuce (those are various chili peppers in the pics, which I tend to 'baby' since germination can take up to 2 weeks as opposed to 2 days for lettuce), as they sprout like mad if I keep the hydroton reasonably moist. The color of the hydroton 'lightens up', letting me know it's starting to get dry. Some lettuce rafts I've hand misted (with a spray bottle), while others I've bottom soaked 2-3 times a day (when not covered to preserve moisture). Both methods have worked equally well for me thus far...

These were also in 1" rafts...

[Gina Cavaliero]

Hey Dino,  agree with everything said so far.  I would definitely try to double up on the 1 inch rafts to try to get to the 2" depth for better overall performance and root health.  Generally trying to start seeds in raft culture will cause a condition called damping off which causes the seedling to rot as it grows at the media line because of too much moisture.  Some will make it but you want optimal germination and starts so it is best to start your seedlings elsewhere.  For best results we have found that insuring the media is well moistened, covered (we just use PE plastic sheeting and tuck it around the tray so it creates a nice greenhouse effect) and insure an average of 70 degrees F.  Once the seedling is at least an inch in size transfer it to your raft.  This also insures you are not wasting valuable space in your system on seedling starts.  A few shelves installed on the wall with adequate lighting will work fine if you have limited space.   

[Dino Pantelidis]

Thanks, I will get a small shelf installed in the corner of my space and sprout there!

Can someone describe "water logging" I've never heard of the term before.

[Vlad Jovanovic]

Basically it means your cubes are too wet. Wet, and not moist.

waterlogged [ˈwɔːtəˌlɒgd]

adj

1. saturated with water

2. (Transport / Nautical Terms) (of a vessel still afloat) having taken in so much water as to be unmanageable

Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003

[TCLynx]

Dripping wet is usually too wet or what one might call waterlogged (imagine the sponge you just lift out of the water)

Seeds like moist or something more like a wrung out sponge (This is the sponge that has been squeezed out but is still moist or damp)

[Chris Smith]

I float my germinated seedling rafts into shallow troughs after a 3 day germ in the shade. For the 3 day germ I place plastic over the rafts after 1 top water which keeps in the moisture. By day 3 lettuce seeds are looking for light and I float them. I an able to do this because of the media that I use. The cinder media has good wicking properties but allows plenty of oxygen to the roots. Once I float a raft I never have to water again. My seeding rafts have 60 holes in a 2x2 square and I start 8 each week. I have been using this method for more than a year now with no rotting issues.

[Dino Pantelidis]

Interesting Chris,

I've seen your previous posts re: cinder media. What else would come close to such a media on the mainland?

Your rafters are 2"?

[TCLynx]

I'm guessing here but I think small lava rock would be similar to his cinder as might expanded shale or expanded slate in it's wicking properties.

[Chris Smith]

I would bet many types of small media might have similar wicking properties. I prefer my starter media in the 1/8 to 1/4 inch range.